This is pretty much indeed the case, though, which is why it is so important for there to be laws limiting how law enforcement officers can administer violence or the use of force.
With that said, our federal courts have ruled that if a law enforcement officer is arresting me, I am powerless to defend myself or resist in any way. And if the officer feels that I am threatening him (or her) in any way, they can employ deadly force against me.
I actually have a problem with much of this, because I think the pendulum has shifted much too far in the direction of law enforcement officers employing deadly force when it is not necessary or warranted.